Nineteen security guards brought in for questioning over the death of a man after a fatal clash outside a popular Gold Coast pub have refused to talk to police.Terrii Tararo, 21, died in hospital after fighting with bouncers at the Fisherman's Wharf Tavern, at Main Beach, on Sunday night.Although a cause of death has yet to be established, police today said it most likely was not (not) due to natural causes.A fight started after Tararo and three of his friends were denied entry to the club.Acting Detective Inspector Nev Huth said 19 security guards had been brought in for questioning, but all had evoked their right to stay silent, on legal advice."We weren't conducting formal interviews with any of those persons," he told reporters on the Gold Coast."They were here, having being required to submit to what would be the commencement of interviews, (but) they have not answered on legal advice any questions relating to this matter."Police ethical standards command is investigating the actions of police officers on the scene.Det Insp Huth said the first police officers on the scene handcuffed Tararo, but removed them moments later when they realised he was limp and unconscious.He made an urgent plea to witnesses to come forward to help shed light on the incident, especially those who may have videoed it on their on their mobile phone.One such video has already been made public by the media, although police said they had not tracked down the owner.Security camera footage from the tavern has been seized by police. AAP